APPENDIX D

Step #1 Determine the heat loss per foot of line.

The startup load can be calculated by determining the amount of heat that is

required to heat the steam pipe from an ambient temperature to the saturation

temperature of the steam the pipe is to carry. This is done by using the

following equation:

= (vp * cp * ? p (tst - Tout))/t; Btu/ft

Q

where:

= ? (ro2- r2); in ft3/ft

vp

Step #2 Determine the pounds of condensate per foot from the heat loss calculated in step #1.

m

= Q/(hst - hcon); lbm/ft

Step #3 Multiply the condensate per foot, calculated in step #2, by the

total number of feet of steam line that slopes toward the drip leg in

question. Then convert the total pounds of condensate to gallons assuming

200 F condensate:

Total Condensate Volume (gallons)=(m*L)*7.49 gallons/ft3

60.1 lbm/ft3

where:

Q

= heat loss per foot of pipe; Btu/hr-ft

Tst

= temperature of steam; deg. F

Tout

= temperature of ambient conditions; deg. F

ro

= outside pipe radius; feet

ri

= inside pipe radius; feet

m

= mass flow rate of condensate; lbm/hr-ft

hst

= enthalpy of saturated steam; Btu/lbm

hcon

= enthalpy of condensate; Btu/lbm

cp

= specific heat of pipe (steel); (0.10 to 0.11) Btu/lbm/degrees F

? p

= density of pipe (steel); (489) lbm/ft3

t

= length of time for startup; hrs (typically 0.5 hrs.)

L

= total length of pipe draining to drip; ft

= volume of pipe material per foot; ft3/ft

vp

D-1